The invention is in the field of multiple photoflash lamp units, such as flashcubes and planar arrays of the type which are adapted to be temporarily attached to a camera in different orientations and which are arranged so that different groups of lamps will be flashed (usually one lamp at a time) in the different orientations of the unit.
U.S. Pat. Nos. 3,598,984 to Stanley Slomski and 3,598,985 to John Harnden and William Kornrumpf disclose a dual-sided flash array having first and second groups of flash lamps and reflectors facing in mutually opposite directions. The array is plugged into the camera whereby the first group of lamps faces frontwardly and is connected for the lamps of that group to be flashed. When these lamps have been flashed, the array is turned around and the lamps of the second group face frontwardly and are connected to be flashed.
The above-referenced patent application of Kurt Weber discloses a multiple flash lamp unit that can be connected to a camera in different orientations in each of which a different group of the flash lamps is relatively farther from the camera lens axis than are the other lamps of the unit. The lamps and electrical circuitry are arranged so that in any of the orientations of the unit with respect to the camera, only the group of lamps relatively farther from the lens axis can be flashed. The concept can be employed in various forms of multiple flash units, such as a double-deck rotatable flash "cube" having connector plugs at each end, or a planar array having a pair of oppositely disposed connector means. The purpose of such an arrangement is to position the "active" group of flash lamps farther above the camera lens, in order to reduce the possibility of a "red-eye" effect that causes the pupils of a person's eyes to appear red or pink in flash pictures taken when the flash lamp is close to the camera lens.
In multiple flash units having such groups of lamps, and especially in units employing high voltage lamps which are flashed by a high voltage pulse (1,000 or 2,000 volts, for example) of low current and energy, there is some possibility that when a firing pulse is applied to the active lamp circuit, sufficient pulse energy may be coupled to the inactive lamp circuit (via stray capacitance in the circuitry, for example) to undesirably flash an inactive lamp in addition to an active lamp.